The number of people killed or seriously injured has jumped from 16 to 47 between 2004 and 2011, says a study from the journalInjury Prevention.

Researchers examined 116 records of people wearing headphones where accidents occurred between them and vehicles from the National Electronic Injury Surveillance System, the U.S. Consumer Product Safety Commission, Google News archives and Westlaw Campus Research.

The victims’ average age was 21 and most (68%) were male. The majority (67%) were under the age of 30. Most (55%) were hit by trains, and 70% of the crashes (the bulk of which were in urban areas) ended in death.

In 74% of the cases police or eyewitness reports said the pedestrian had headphones on when hit. And 29% of reports made mention or horns or sirens going off before the crash.

The study’s authors noted that the “sensory deprivation” and distraction that occurs when pedestrians wear headphones are the leading reasons why they’ve seen a spike in accidents.

Richard Lichenstein told Science Daily that headphone usage often results in people not receiving aural cues (ie., honking horns, blaring sirens from vehicles) that would normally prevent such accidents.

“Everybody is aware of the risk of cell phones and texting in automobiles, but I see more and more teens distracted with the latest devices and headphones in their ears,” says lead author Richard Lichenstein, M.D., associate professor of pediatrics at the University of Maryland School of Medicine and director of pediatric emergency medicine at the University of Maryland Medical Center. “Unfortunately as we make more and more enticing devices, the risk of injury from distraction and blocking out other sounds increases.”

More comprehensive research is needed to determine which groups of people face the greatest risks, experts say.

Given that the headphone industry is valued at more than $1 billion with brands such as Beats by Dr. Dre leading the pack, this study may alert consumers to certain risks that may exist when listening to headphones while walking.

Will this study’s findings change your listening habits? Let us know in the comments.